RFR: 8262341: Refine identical code in AddI/LNode. [v2]

[Roland Westrelin]

> AddINode::Ideal() and AddlNode::Ideal() are almost identical but the
> same logic had to be duplicated because AddINode::Ideal() tests its
> inputs for Op_AddI, Op_SubI etc. while AddLNode::Ideal() tests for
> Op_AddL, Op_SubL etc. This patch refactors the code so the common
> logic is in a single method parameterized by a BasicType argument.
> 
> The way I've done this before in the context of int/long counted loops
> was to use and extra virtual method operates_on(). So:
> 
> n->Opcode() == Op_AddI becomes n->is_Add() && n->operates_on(T_INT)
> 
> Working on this change made me realize that pattern doesn't work that well:
> 
> - it's quite a bit more verbose and converting existing code is not as
>   mechanical as we would like to avoid conversion errors.
> 
> - it breaks when a class has a subclass. For instance AddNode has
>   OrINode and OrLNode as subclasses so testing for n->is_Add() returns
>   true with an OrI node.
> 
> Instead, this change introduces new functions. For instance of
> AddI/AddL:
> 
> int Op_Add(BasicType bt)
> 
> that returns either Op_AddI or Op_AddL depending on bt. This made
> refactoring the AddINode::Ideal() logic straightforward. I removed all
> use of operates_on() as well and converted existing code to the new
> Op_XXX() functions.

Roland Westrelin has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - T *p to -> T* p
 - Merge branch 'master' into JDK-8262341
 - fix

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6607/files
  - new: https://git.openjdk.java.net/jdk/pull/6607/files/5160efe2..22292277

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6607&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6607&range=00-01

  Stats: 11456 lines in 535 files changed: 7400 ins; 1974 del; 2082 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6607.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6607/head:pull/6607

PR: https://git.openjdk.java.net/jdk/pull/6607